Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759518Ab3IDSJI (ORCPT ); Wed, 4 Sep 2013 14:09:08 -0400 Received: from b232-35.smtp-out.amazonses.com ([199.127.232.35]:30822 "EHLO b232-35.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753493Ab3IDSJG (ORCPT ); Wed, 4 Sep 2013 14:09:06 -0400 Date: Wed, 4 Sep 2013 18:09:04 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Will Deacon cc: Tejun Heo , "akpm@linuxfoundation.org" , Russell King , Catalin Marinas , "linux-arch@vger.kernel.org" , Steven Rostedt , "linux-kernel@vger.kernel.org" Subject: Re: [gcv v3 27/35] arm: Replace __get_cpu_var uses In-Reply-To: <20130904174624.GB5599@mudshark.cambridge.arm.com> Message-ID: <00000140ea29d3c8-5110dd9f-9dcf-470f-9b7e-4e7ff0874052-000000@email.amazonses.com> References: <20130828193457.140443630@linux.com> <00000140c67834c9-cc2bec76-2d70-48d1-a35b-6e2d5dedf22b-000000@email.amazonses.com> <20130830100105.GF25628@mudshark.cambridge.arm.com> <00000140e4440576-ae4236ee-3073-4f94-b569-d17396e57513-000000@email.amazonses.com> <20130904093335.GA8007@mudshark.cambridge.arm.com> <00000140e9557be9-1523eeab-c0f6-45a0-881c-9336a8a6cf85-000000@email.amazonses.com> <20130904142324.GD3643@mudshark.cambridge.arm.com> <00000140e97747d2-ee164a4d-d692-409a-a919-083eff3a41ca-000000@email.amazonses.com> <20130904174624.GB5599@mudshark.cambridge.arm.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 199.127.232.35 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 738 Lines: 20 On Wed, 4 Sep 2013, Will Deacon wrote: > On ARM, yes. I'm worried that there may be an architecture where the change- > or-fail operation would only fail if the access from the interrupt handler > *also* used that change-or-fail instruction, which isn't the case with > this_cpu_inc. > > I have no idea if such an architecture exists :) Atomic operations use atomic_t. this_cpu operations can only use regular scalars. So the set of variables that are updated by each should be distinct. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/